Acquiring torque measurements on rotating equipment at high revolution rates may expose rotating electronic components to massive centrifugal forces. For example, a 4 inch (10.16 cm) diameter shaft rotating at 9600 revolutions per minute (RPM) has 5200 gravitational forces (also referred to as G-forces or Gs) at the surface of the shaft. As electronics are mounted above the shaft surface, the forces increase exponentially with an increasing radius of rotation. For example, electronics weighing 10 grams, mounted 1 inch above the surface of the example shaft will be exposed to 7850 Gs, and 173 lbs (about 769.5 N) of centrifugal force. Centrifugal forces are problematic and limit the life and/or tolerance of circuit components or elements.
Limiting factors for tolerance of such forces in traditional electronic circuits typically include utilizing timing control circuits with crystals, and any other non-solid state components such as electrolytic capacitors containing liquids, and micro-electro-mechanical (MEMs) devices. Modern solid dielectric capacitors may easily be substituted for electrolytic types in circuits where high centrifugal forces are anticipated. However, using digital and embedded systems electronics is more difficult without crystals.
Resistor-capacitor (RC) oscillators are unaffected by centrifugal forces. In some conventional devices and systems, RC oscillators are utilized in high-G digital circuits where precise timing, normally critical for communications, is not needed due to use of clocked synchronous data encoding formats. Even though RC oscillators drift much more with temperature than crystal controlled oscillators, synchronous data encoding formats that multiplex the data rate clock with the data stream are tolerant of much more drift than is typical of RC timing control. A problem occurs, however, when precise timing is needed and must be maintained.
For example, with the onset of Voltage to Frequency Converter (VFC) type analog systems, precise timing must be maintained for accuracy of the information being converted to the frequency domain. Analog systems are desirable in applications where simplicity and high bandwidth are required and in high reliability and safety critical applications where the complexity of software and firmware must be scrutinized to Design Assurance standards, such as DO-178.
Accordingly, a need exists for remotely powered and remotely interrogated torque measurement systems, devices, and/or methods that may be implemented entirely in the analog domain.